Sago kamsusŏng ŭl pakkunŭn suŏp ŭi chŏngch'iYun, Yang-su (Elementary school teacher), Chong-hŭi Wŏn, Chang, Kun (Elementary school teacher) · First published 2015Open the Tome
Chawŏn mit hwanʼgyŏng kwalli chŏngchʻaek ŭi pyŏnhwa kwaje /Yun Yang-su... [et al.].Yang-su Yun · First published 1998Open the Tome
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